(1) Field of the Invention
This invention relates to a pulse generator of the type comprising a capacitor, means for periodically discharging the capacitor to generate pulses of electricity and means for recharging the capacitor between pulses. The invention is particularly developed for use in supplying pulses to a microwave tube such as a magnetron in a radar transmitter.
In pulse generators of the aforementioned type the capacitor can develop a reverse charge under fault conditions usually related to sparking in the tube. This reverse charge can vary from a small inconsequencial value up to a value equal to the original forward charge. Large reverse charges can present a problem because they can lead to damaging transients which lead to circuit failure.
(2) Description of the Prior Art
The above problem has been dealt with in the past by the connection of a diode and resistor in series across the capacitor. This bleeds away the negative charge. Normal design practice requires the diode and resistor to be rated to handle the mean power of the modulator system. In a large radar transmitter this could be for example ten kilowatts. This generates new problems because the resistor is expensive, it generates substantial heat under fault conditions, it is bulky, and it is not easily integrated into modern solid state equipment. There is also of course considerable energy wastage.